How long did dinosaurs live?

How long did dinosaurs live?

Dinosaurs have left a lot of information in their fossils, including how they defended themselves, what they ate, and sometimes, how they died. But when these great beasts died, did they leave any clues as to how old they were at the time of death, indicating whether they were young, middle-aged, or old?

Growth rings in the fossilized bones of dinosaurs contain information about their age. These rings, which were created by the method of tree rings, were discovered in recent decades and have shown that most non-avian dinosaurs, although they sometimes reached very large sizes, did not live long. For example, the growth rings of Sue, a large tyrannosaur fossil housed at Chicago’s Field Museum of Natural History and one of the most complete specimens of T. rex ever discovered, show that the dinosaur died at 28 years old.

Thomas Holtz, a vertebrate paleontologist at the University of Maryland Live Science “The herbivorous duckbill dinosaurs seem to have lived only a decade or two,” he said. “A lot of people might think that at least some dinosaurs got really big because they lived so long,” said Steve Brust, a vertebrate paleontologist at the University of Edinburgh in Scotland. “Scientists used to think the same.”

Today’s large animals are usually long-lived. African bush elephant (Loxodonta africana(as the largest living land animal on earth can live up to 70 years and polar whales)Balaena mysticetus) can live up to 200 years.

The story of dinosaurs is different. Holtz explained that a thin section of the dinosaur bone had a series of parallel lines caused by the outward growth of the bone. A new line is created every year, so counting these lines gives an accurate estimate of the animal’s age. These lines are created by annual changes in the way animals grow. In the spring and summer, warm weather and abundant food means that animals have enough nutrition to allow them to grow faster. But in winter, when the weather is cold and food is scarce, it grows slowly. This slowness manifests itself in the form of lines between the bone layers.

Tyrannosaurus lived less than today’s elephants

The method of measuring growth with the help of bone rings also has problems, one of which is the problems caused by the medullary cavity. The medullary cavity is a chamber in the middle of the bone where bone marrow is produced. As the bone grows, the medullary cavity also grows, thus clearing some of the initial growth rings. To overcome this problem, researchers can place the bones of smaller members of the same species on the missing lines of larger individuals to estimate the total number.

Another issue is the type of bone. Some bones are better for counting growth rings than others. Ribs or bones such as the fibula that do not bear a lot of pressure or weight show the growth history more clearly.

While dinosaurs did not live as long as some of today’s large animals, there are similarities. For example, larger animals tend to live longer than smaller animals, and this is also true of dinosaurs.

Reptiles (a group of long-necked leaf-eating dinosaurs that include the largest dinosaurs that ever lived) had the longest lifespans of all dinosaurs, with the oldest known sauropods living around 60 years. On the other hand, a genus of troodontids named Stenonychosaurus unequalis With a weight of 50 kg, it reached its maximum size in just three years and probably did not live long after that.

read more

There are many ideas as to why dinosaurs were short-lived. Perhaps their metabolism (or their body’s chemical processes, including the conversion of calories into energy) played a role, Brust says. Some dinosaurs were at least partially warm-blooded and had fast metabolisms that could have led to rapid growth and early death.

Perhaps the reproduction of dinosaurs was involved in their short life span. Many dinosaurs produced very large clutches of eggs, which meant that they produced many offspring in a short period of time. On the other hand, long-lived mammals such as elephants and whales reproduce more slowly, so natural selection for longer lifespans operates.

However, the assumption of a link between reproduction and short life span is not without problems. For example, Galapagos tortoises (Chelonoidis niger) can produce large clutches of eggs while being long-lived, so producing more offspring at once does not always indicate a shorter lifespan.

Finally, we still don’t know why non-avian dinosaurs died young.

Source link


No comments yet. Why don’t you start the discussion?

Leave a Reply

Your email address will not be published. Required fields are marked *